The present invention relates to methods and apparatus for winding or rewinding a running web of material into rolls. More particularly, the present invention relates to methods and apparatus for winding a web of material that is running from a web handling operation and that is to be wound sequentially about the center core shaft of one roll and then about the center core shaft of another roll without stopping the running web.
Various apparatus for winding or rewinding running webs into rolls are known. Basically such apparatus falls into two general classes; surface winders, and core winders. Surface winders generally have a drum that has a uniform diameter, and the roll of web material being wound is forced against the outer surface of the drum. This allows the use of smaller horsepower (for example, 4 horsepower), cost effective motors. In contrast and due to the build-up ratio, a comparable core winder might require a 40 horsepower motor. The difference in motor sizes results in a significant difference in the costs for the winders. Largely because of this cost difference, surface winders have been generally preferred by cost conscious purchasers.
Surface winders have, however, had long recognized disadvantages. For instance, they cannot be used with web materials whose surfaces cannot or should not be touched during the winding operation. Additionally, satisfactory tapered tension control is more difficult, and thus more expensive, to achieve in surface winders as compared to core winders. Those working in the art have long sought a winder, without the disadvantages of surface winders, that would be more cost competitive with surface winders.
Conventional core winders have other disadvantages, besides cost, vis-a-vis surface winders. Typical turret-type core winders tend to be large and require space to accommodate the swinging of their roll bearing arms through the approximately 180.degree. arcs. Additionally, turret type core winders require another motor to affect the movement of their roll bearing arms, as well as mechanisms to attempt to assure the proper level and angular alignment of the rolls after such movement, particular where high quality rolls are being wound. This adds to the cost of the core winders. Again, those working in the art have also sought a core winder that would be cost competitive with surface winders and that would not have these aforementioned disadvantages.